1. Field of the Invention
The present invention relates to a guidance method of flood water for protecting, from flood water, a specific zone where a general residence and public facility, such as a school are built, as a safety zone. The invention also relates to a guidance system of flood water used for carrying out the guidance method.
2. Description of the Prior Art
One of the basic plans of Japanese river improvement administration is to flow rain water or flood water to the sea swiftly. Another basic plan is not to collect the rain water and not to flow the water at once. In accordance with these basic plans, many rivers were repaired in the shape of a straight line, and the banks were restrained by a stone wall and concrete. Morever, many dams have been built at the upstream of a big river.
It is granted that drainage of the river which was modified into a straight shape and having banks restrained by means of concrete has been enhanced. Further, it is also granted that a dam is built at upstream and flood of river has been prevented in some degree. However, natural environment of mountain where the dam was built is destroyed, and the river where the bank was restrained by means of concrete, stone wall, and the like, is turned into the artificial waterway. And the fishes living in river decrease in number, and the animals living around the bank of river are extinct or seriously endangered. Even if river improvement which destroys environment is carried out, damage by a flood is caused like Tokai heavy rain on September, 1999. It must be granted that there is a limit in the river improvement method for collecting flood water or rain water into a dam, and in the river improvement method for pushing rain water into river. The above fact is recognized in the U.S. and Europe, and it is granted that there is a possibility that river overflows, and the river improvement method has been changed into a direction that does not oppose the nature. In reply to this change, Japanese River Council of the Ministry of Construction submitted a response at the end of 1999 to the effect that the river improvement should be proceeded in the entire drainage area on the assumption that a river floods.
The present invention has been accomplished in view of the above facts of flood and the reply, and it is an object of the present invention to provided a guidance method of flood water for protecting and a guidance system of flood water used for carrying out the guidance method which protects, from flood water, specific zones where general residences and public facilities such as schools are built, as safety zones even if river or sea water overflows. More specifically, it is an object of the invention to provide a guidance method of flood water for protecting and a guidance system of flood water used for carrying out the guidance method in which specific zones are protected as safety zones from the flood water without deteriorating landscapes of the specific zones. In addition to the above object, it is another object of the invention to provided an inexpensive guidance method of flood water for protecting and an inexpensive guidance system of flood water used for carrying out the guidance method in which a specific zone is protected as a safety zone from the flood water even at the time of power failure.
The above objects are achieved by a structure in which a guidance plate is buried in underground where it is expected to be upstream of water flow when a bank of river, reservoir or port is destroyed, and the guidance plate is raised to a surface of earth when the flood water flows, or flowed or is expected to flow, thereby guiding the flood water into a predetermined direction by means of the guidance plate. Further, relatively high-rise buildings such as school and building are equipped with water tanks such as water tank and tank for disaster prevention. Therefore, the water in such a water tank may be used. If the water in the water tank is used, the guidance plate can be driven upwards also in case of emergency when tap water can not be obtained. To achieve the above objects, according to a first aspect of the present invention, there is provided a guidance method of flood water wherein a guidance plate is laid under underground in the vicinity of upstream side of a specific zone where a general residence, a school, a public facility like a hospital or the like is built and where it is anticipated that the flood water flows, and when flood water is generated, or when there is a possibility that flood water may be generated, the guidance plate is raised to a predetermined height of surface of the earth, a specific zone is secured as a safety zone by diverting the flood water from the specific zone by means of the raised guidance plate, and by guiding the flood water to a retarding basin, a drainage canal, and the like. According to a second aspect of the invention, the guidance plate is raised by water pressure, such as tap water and impounded water. According to a third aspect of the invention, there is provided a guidance system of flood water comprising a guidance plate provided under underground in the vicinity of upstream side of a specific zone where a general residence, a school, a public facility like a hospital or the like is built and where it is anticipated that the flood water flows, the guidance plate diverting the flood water from the specific zone and guiding the flood water to a retarding basin, a drainage canal, and the like, and the guidance system further comprising a drive system for driving the guidance plate to a predetermined height position of surface of the earth, wherein the drive system comprises a piston cylinder unit which is operated by water pressure such as tap water and impounded water.